Many useful chemicals can be toxic to the platform organisms proposed to toxicity, by regulating the transcription of ‘stress’ genes to either enhance or decrease the levels of certain gene products. Escherichia coli is a well studied microorganism with a completed genome sequence commonly used in the chemical industry. However, approximately 60% of predicted genes in the genome have unknown function.
Ethanol is a commodity chemical with an annual market of $15 billion and a current production of 2 billion gallons in the United States alone. It is used to make plastics, fibers, resins, and also as a renewable energy source to reduce the national dependence on foreign nonrenewable sources. Ethanol can be blended with gasoline up to 85% to create a cleaner burning fuel for automotives. Ethanol is commonly produced from fermentation of simple sugars or corn fibers. The first successful report of using recombinant Escherichia coli to produce ethanol was in 1989. Subsequent innovations on the process have lead to extremely high titers. Unfortunately, increased alcohol concentrations have shown to be toxic to microorganisms, limiting the production possibilities.
Therefore, there is a need for increased tolerance of microorganisms, such as E. coli, to alcohol in order to improve microbial production processes of ethanol.